Idle control system



March 18, 1958 M. J. KITTLER IDLE CONTROL SYSTEM Filed April 25, 1955 INVENTOR.

' MILTON J.K|TTLEH W/ ATTORNE S United rates atent bull.

mLE CQNTRGL YSTEM Milton 3. Kittler, Detroit, Mich, assignor to Holley Carburetor Company, Detroit, Mich, a corporation of Michigan Application April 25, 1955, Serial No. sas es Claims. (Cl. 261-23) The present invention relates to an idle control system for a carburetor.

Modern V-8 engines equipped with two stage, four barrel carburetors frequently do not idle smoothly and are prone to stumble or stall when returning to idle speed after having been operated at some higher speed. Among various causes which contribute to this type of trouble is the unequal fuel distribution caused by the construction of a typical four barrel, two stage carburetor, and also the great amount of volume in the large intake manifolds which are used with such four barrel carburetors.

While the present invention is particularly effective in eliminating the ditficulties referred to in V'8 engines equipped with two stage, four barrel carburetors, it is also applicable and useful in connection with single stage carburetors having any required number of barrels and is useful in carburetors connected to any type of gasoline internal combustion engine.

With the foregoing remarks in mind, it is an object of the present invention to provide carburetors characterized by the inclusion of idle control means effective to produce smooth idling and to prevent stumbling or stalling when the engine is returned to idle speed after having been operated at some higher speed.

More specifically, it is an object of the present invention to provide a carburetor having an additional control air passage to supply additional air to the usual primary idle fuel supply passage at a point just prior to discharge of the idle passage into the barrel of the carburetor.

It is a further object of the present invention to provide idle control means in a carburetor comprising an air supply passage having an intake port at the side of the barrel of the carburetor adjacent an edge of the usual throttle plate therein and having a discharge connection into the usual primary idle fuel supply passage at a point just prior to the discharge of the fuel supply passage into the barrel of the carburetor.

It is a further object of the present invention to provide idle control means effective to increase atomization of fuel and velocicty of discharge of the atomized fuel and air mixture into the barrel of the carburetor.

it is a further object of the present invention to provide idle control means as described in the preceding paragraph which are alfected by the position of the throttle plate so as to be or become elfective when the throttle plate is closed or substantially closed.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings, wherein:

Figure l is a side elevational view partly in section along the section line indicated at l-Ii, Figure 2.

Figure 2 is a fragmentary bottom plan view of the carburetor shown in Figure 1.

Figure 3 is a fragmentary sectional view showing a modification of the invention.

Figure 4 is a fragmentary sectional view similar to Figure 3 showing yet another modification of the present invention.

The carburetor partly illustrated in Figures 1 and 2 may be considered as a two stage, four barrel carburetor in which the primary barrel is indicated at it. and the secondary barrel is indicated at 12. It will be appreciated that an additional primary and secondary barrel are pro vided but since the application of the idle control means to the remaining two barrels is identical, it is not illustrated or described.

The carburetor illustrated is of the down-draft type and the primary and secondary barrels are provided with pivoted throttle plates 14 and 16 respectively. Suitable means for supplying fuel to the barrels are indicated generally at 18 and 20.

As is conventional, primary idle fuel supply means are provided and these means comprise a primary idle fuel supply passage 22 having a branch 24 communicating with the primary barrel it at the upstream side of the throttle plate 14. Adjustment of the idle fuel supply is effected by a needle valve 26 cooperating with a chamber 23 connected by a short passage 39 to a recess 32 at the bottom of the carburetor. The idle fuel mixture entering the recess 32 follows the channel 34 provided at the underside of the carburetor to branch channels 36 and which lead respectively to the primary and secondary barrels ll? and 12. It will be appreciated that in as bly the carburetor is mounted on a flat supporting sur forming bottom closures to the recess 32 and chann l 36 and 38, thus converting the latter into closed pa In accordance with the present invention idle control air supply means are provided and as illustrated in Figures 1 and 2, this comprises a passage 4% having an intake port 42 in the side of the primary barrel 1%) upstream from the throttle plate 14 when the throttle plate is in closed posit on. The passage 46 has a calibrated restriction id communicating with the passages formed by the branch channels 36 and 38. It will be observed that the discharge restriction 44 of the idle control air passage is closely adjacent to discharge ports 46 and of the primary idle fuel supply system.

The flow of air when the idle control air supply passa e is operative, greatly increases the velocity and hull; of primary idle fuel supply. Observation of the carburetcr under laboratory test conditions shows that the flow of idle mixture from ports 56 and 48 into the throttle barrels 1d and 12 respectively, is very much smoother and better distributed. The metered restriction through which the idle control air supply flows into the idle fuel supply system regulates the quantity of air, and the p cise results obtained by the operation of the invention can be determined by this restriction.

The intake port 42 of the idle control air passage it) is located in the side of the barrel 16 at the upstream side of the throttle plate 14 and adjacent an edge of the plate in a. position such that the adjacent edge of the throttle plate moves away from the port on initial opening movement of the throttle. Under these circumstances there is a continuous flow of air through the passage 4ft both when the throttle is completely closed and when it is partially open. As a result, the flow of air through the passage ill remains substantially constant for small changes in throttle opening and thereafter has no appreciable effect on the mixture ratio. It does however, give the improved atomization and increased velocity and improved discharge pattern of the idle mixture as described above. When the statement is made that th flow through the passage 49 has no appreciable efiect on mixture ratio, it is of course understood that the initial leaning out caused by the addition of air into the idle system by the passage 40 will have been compensated for in the initial calibration of the carburetor, and the movement of the throttle plate.

mixtures are not then further altered by the flow through i plate lid closed, substantially equal pressures exist at the intake port 54 and the discharge port 44 of the air supply passage an and accordingly, it is substantially ineffective when the throttle plate is in closed; or nearly closed position. The intake port 54 is in a, position such that initial opening movement of the throttle plate 14 will cause its adjacent, edge to move across the port54 and so in effect to transfer the intake port from thedownstream side of the throttle plate to the upstream side thereof. 7 V

' With the parts in the position illustrated in Figure 3, when the throttle plate is closed or nearly closed, it will be appreciated that the engine is running at a low idle speed. If the engine speed'is accelerated by opening the throttle, the, edge of the throttle plate 1'4 will selectively expose intake port'54 to the relatively high pres sure region existing in the carburetor above the throttle plate 1 3. This causes a flow of air entering port 54, flowing through passage 40 and discharging into the idle fuel supply system through the port 4 This in turn produces two immediate etfects, one being a leaning out of the idle mixture and the other'being a better atom ization and discharge pattern ofthe idle mixture due to the added air fiow which tends to both atomize the fuel more completely and also to cause it to move at a higher velocity through the branch passages formed by channels 36 and 38 and thence to the barrels 10 and 12. respectively. The operation of the embodiment of the invention illustrated in Figure 3 is thus to be contrasted with the operation of the system disclosed in conjunction with Figures 1 and 2. In the embodiment of Figure 3, the flow through the passage 4% changes drastically as the throttle moves slightly from fully closed position, thus varying both the mixture ratio and the atomization, ve-

locity and discharge pattern of theidle fuel mixture. In

fact, it is possible by proper design of the passage and port as to size and restrictions therein that. the flow of idle fuel mixture could be stopped altogether when the throttle plate 14 opens to a position where intake port 54 is completely exposed. 7

Referring now to Figure 4 there is illustrated an ar rangernent in which the idle control air supply passage as is provided with two branch passages comprising an upper branch terminating in a port 42 located at the upstream side of the throttle plate 14, and a second branch passage having an intake port 54 located at the downstream side of the throttle plate 14. Intake ports 42 and 54 are adjacent a movable edge of the throttle plate and so located that the intake port 42' remains at the upstream side of the throttle plate during opening movement thereof, but the intake port 54 is traversed by the adjacent edge of the throttle plate during initial opening and hence, in eifect is transferred from the downstream side to the upstream side during initial'opening Conversely, intake port 54 is transferred from the upstream side to the downstream side of the throttle plate during the last stages of the movement of the throttle plate to fully closed position. The operation of the system illustrated in Fig ure 4 may represent a combination of features of the embodiments illustrated in Figures 1 and 2, and in, Figure 3, and the relative effectiveness of the difierent fea- The drawings and the foregoing specifiCation consti-..-

V tute a description of the improved idle control system trolling flow through said fuel supply passage, an idle control air passage having an intake port in said barrel at the downstream side of said throttle plate when the throttle is closed and in position to be transferred to the upstream side of said throttle plate upon initial throttle opening movement and communicating with said primary idle fuel supply passage adjacent its aforesaid discharge port and between said discharge port and said needle valve. 7

2. A carburetor comprising a barrel having athi'ottle plate therein, a primary idle fuel supply passage having a discharge port opening into. said barrel at the downstream side of said throttle plate, a needle. valve. controlling flow through said fuel supply passage, an idle control air passage having branched inlet passages connected to inlet ports in said barrel, one of said inlet ports being located at the upstream side of said throttle plate when the throttle is closed and in position to remain at the upstream side thereof during throttle opening movement, and the other of said inlet ports beinglocated at the downstream side of said throttle plate when the throttle is closed and in position to betransferred to the upstream side of said throttle plate upon initial throttle opening movement, said air passage communicat ing with said primary idle fuel supply passage adjacent its aforesaid discharge port and between said discharge port and said needle valve.

3. A two stage carburetor having primary and secondary barrels, throttle plates in said barrels, a primary idle fuel supply passage having short branch passages having discharge ports in said barrels at the downstream side of the throttle plates therein, a needle valve controlling flowthrough said fuel supply passage, an idle control air pas sage having an inlet port inthe primary barrel adjacent an edge of the throttle plate therein at the downstream side of said throttle plate when the throttle is closedv and in position to be transferred to the upstream. side of said throttle plate upon initial throttle opening movement and communicating with said; branch passages between said needle valve'and the aforesaid discharge-ports.

4. A two stage carburetor having primary and. second-r ary barrels, throttle plates in said barrels, a primary idle fuel supply passage having short branch passages having discharge ports in said barrels at the downstream side of the throttle plates therein, an idle control air passage having branched inlet passages connected to inlet ports in said barrel, one of said inlet ports being located at the upstream side of said throttle plate when the throttle is.

closed and in position to remain at the upstream side there-: of during throttle opening movement, and the other of said inlet ports being located at the downstream side of said throttle plate when the throttle is closed and imposition to be transferred to the upstream side of said throttle plate upon initial throttle opening movement, said idle control air passage being connected to said idle'fuel supply branch passages downstream from 'said needlevalve.

5. A two stage carburetor having primary and secondary barrels located adjacent each other and havinga com-' mon Wall, throttle plates in said barrels, an idle fuel supply passage having a needle valve for adjusting the flow therethrough, said passage communicatingwith a shorttransverse passage extending across said common wall. and terminating in ports in said barrels downstream from said throttle plates, an idle; controlair passagehav-ing a single inlet which is in said primary barrel downstream fromv the throttle-platetherein in position to be transferred to the upstream side thereof upon initial opening movement of said throttle plate, said idle control air passage having a restricted outlet port connecting with said first mentioned passages at the junction thereof.

6. A carburetor comprising a body having a fiat end surface for mounting on a flat support and having two barrels adjacent each other, throttle plates in said barrels, idle fuel supply means comprising a short channel in said flat end surface extending directly between said barrels,

a longer channel in said flat end communicating at one end with said short channel midway between its ends, an idle fuel supply passage communicating at one end with said longer channel remote from its connection to said short channel, an idle control air passage having an inlet port disposed to receive air at the higher pressure existing above one of said throttle plates and an outlet port communicating directly with said short channel substantially midway between the ends thereof, said channels being closed to form passages when said carburetor is mounted on a flat support.

7. A carburetor as defined in claim 6 in which the outlet port of said idle control air passage is disposed to discharge air generally perpendicularly to said short channel.

8. A carburetor as defined in claim 6 in which the outlet port of said idle control air passage is disposed to discharge air generally perpendicularly to said short channel and generally perpendicularly of said longer channel at its point of connection to said short channel.

9. A carburetor as defined in claim 6 in which the outlet port of said idle control air passage has a restriction to discharge air at high velocity into the idle fuel mixture just before it passes to said barrels.

10. A two-stage carburetor having primary and secondary barrels, throttle plates in said barrels, a primary idle fuel supply passage having short branched passages having discharge ports in said barrels at the downstream side of the throttle plates therein, a needle valve controlling flow through said idle fuel supply passage, an idle control air passage having a single inlet port which is located in the primary barrel adjacent an edge of the throttle plate therein at the downstream side of the throttle plate when the throttle is closed and in position to be transferred to the upstream side of said throttle plate upon initial opening movement thereof and communicating with said branch passages between said needle valve and the aforesaid discharge ports.

References Cited in the file of this patent UNITED STATES PATENTS 2,120,970 Allen June 21, 1938 2,208,864 Farr July 23, 1940 2,296,697 Ball Sept. 22, 1942 2,297,109 Moseley Sept. 29, 1942 2,376,228 Brown May 15, 1945 2,580,294 Grifion Dec. 25, 1951 2,621,911 Lindsteadt Dec. 16, 1952 2,689,115 Olson Sept. 14, 1954 2,745,645 Kittler et a1. May 15, 1956 2,752,132 Nye June 26, 1956 

